A new processing method,equal channel angular pressing(ECAP)plus cold rolling(CR),was applied to producing ultra-fine grained FeCoV alloy.The microstructures of ultra-fine grained FeCoV alloy after ECAP,ECAP plus CR,a...A new processing method,equal channel angular pressing(ECAP)plus cold rolling(CR),was applied to producing ultra-fine grained FeCoV alloy.The microstructures of ultra-fine grained FeCoV alloy after ECAP,ECAP plus CR,and the effect of tempering treatment on the microstructure of FeCoV alloy produced by ECAP plus CR were investigated.The results show that an elongated substructure with a width of about 0.3μm is obtained after four-pass ECAP using Route A.Cold rolling after ECAP cannot change the morphologies of elongated substructure,and it results in higher fraction of high-angle boundaries and higher dislocation density compared with the identical ECAP without rolling.Subsequent tempering for 30 min at 853 K brings about many nano-phases precipitating at subgrain boundaries and insides the grains,and the size of precipitated phase is measured to be about 10 nm.Nano-phases grow up with increasing tempering temperature and equiaxed structure forms at 883 K.展开更多
Nanocrystalline 2J4 alloy was fabricated by equal-channel angular pressing (ECAP). Microstructural evolution at different passes of ECAP and the effect of angle (φ) on the ECAP were researched. The results reveal th...Nanocrystalline 2J4 alloy was fabricated by equal-channel angular pressing (ECAP). Microstructural evolution at different passes of ECAP and the effect of angle (φ) on the ECAP were researched. The results reveal that α phase slowly turns to γ phase and follows the formation of dislocation cells in the 2J4 alloy with increasing severe plastic deformation. At last, it becomes reasonably finer bands of subgrains. The results with intersect at angle (φ) of 90° are better than that at angle (φ) of 120°. After three passes of ECAP, at angle φ of 90°, nanocrystalline microstructure can be obtained. The grain size is reduced from 30μm in the initial state to 400nm.展开更多
The flow stress behavior of aluminum alloy 6A10 was studied by the hot compression tests at temperatures from 350℃ to 550 ℃ and strain rates from 0.1 s^-1 to 10 s^-1 with Gleeble-1500 thermo-mechanical simulator. Th...The flow stress behavior of aluminum alloy 6A10 was studied by the hot compression tests at temperatures from 350℃ to 550 ℃ and strain rates from 0.1 s^-1 to 10 s^-1 with Gleeble-1500 thermo-mechanical simulator. The result demonstrates that the temperatures of specimen differ from initial ones affected by deformation conditions, and that the softening mechanism is dynamic recovery. A new approach was proposed to analyze the flow stress character directly from actual stress, strain, temperature and strain rate data, without performing any previous flow stress correction caused by temperature variation. Comparisons between the experimental and predicted results confirm that the established flow stress model can give reasonable estimation, indicating that the mentioned approach can be used in flow stress model analysis of the materials that undergo only dynamic recovery based on the data obtained under variable deformation temperature.展开更多
The dynamic recrystallization(DRX) behaviors in SPHC steel were investigated with hot compression tests at deformation temperatures of 950-1 150,strain rates of 0.1-15 s-1,and initial austenite grain sizes of 86-232 ...The dynamic recrystallization(DRX) behaviors in SPHC steel were investigated with hot compression tests at deformation temperatures of 950-1 150,strain rates of 0.1-15 s-1,and initial austenite grain sizes of 86-232 μm.The effects of deformation temperature,strain,strain rate and the initial austenite grain size on the microstructural evolution during DRX were studied in detail.The results show that DRX is observed under the condition of the Zener-Hollomon parameter being less than 1.07×10 13 s-1.The deformation activation energy for SPHC steel is calculated to be 299.4 kJ/mol by regression analysis.Austenite grain size of DRX is refined with decreasing temperature and increasing strain rate under steady state conditions,but it is not influenced by the initial grain size.The mathematical equation of DRX grain size of SPHC steel is obtained.展开更多
基金Project(50675133)supported by the National Natural Science Foundation of ChinaProject(2006CB705401)supported by the National Basic Research Program of China
文摘A new processing method,equal channel angular pressing(ECAP)plus cold rolling(CR),was applied to producing ultra-fine grained FeCoV alloy.The microstructures of ultra-fine grained FeCoV alloy after ECAP,ECAP plus CR,and the effect of tempering treatment on the microstructure of FeCoV alloy produced by ECAP plus CR were investigated.The results show that an elongated substructure with a width of about 0.3μm is obtained after four-pass ECAP using Route A.Cold rolling after ECAP cannot change the morphologies of elongated substructure,and it results in higher fraction of high-angle boundaries and higher dislocation density compared with the identical ECAP without rolling.Subsequent tempering for 30 min at 853 K brings about many nano-phases precipitating at subgrain boundaries and insides the grains,and the size of precipitated phase is measured to be about 10 nm.Nano-phases grow up with increasing tempering temperature and equiaxed structure forms at 883 K.
文摘Nanocrystalline 2J4 alloy was fabricated by equal-channel angular pressing (ECAP). Microstructural evolution at different passes of ECAP and the effect of angle (φ) on the ECAP were researched. The results reveal that α phase slowly turns to γ phase and follows the formation of dislocation cells in the 2J4 alloy with increasing severe plastic deformation. At last, it becomes reasonably finer bands of subgrains. The results with intersect at angle (φ) of 90° are better than that at angle (φ) of 120°. After three passes of ECAP, at angle φ of 90°, nanocrystalline microstructure can be obtained. The grain size is reduced from 30μm in the initial state to 400nm.
基金Project(50675133) supported by the National Natural Science Foundation of ChinaProject(2006CB705401) supported by the National Basic Research Program of China
文摘The flow stress behavior of aluminum alloy 6A10 was studied by the hot compression tests at temperatures from 350℃ to 550 ℃ and strain rates from 0.1 s^-1 to 10 s^-1 with Gleeble-1500 thermo-mechanical simulator. The result demonstrates that the temperatures of specimen differ from initial ones affected by deformation conditions, and that the softening mechanism is dynamic recovery. A new approach was proposed to analyze the flow stress character directly from actual stress, strain, temperature and strain rate data, without performing any previous flow stress correction caused by temperature variation. Comparisons between the experimental and predicted results confirm that the established flow stress model can give reasonable estimation, indicating that the mentioned approach can be used in flow stress model analysis of the materials that undergo only dynamic recovery based on the data obtained under variable deformation temperature.
基金the National Natural Science Foundation of China (No. 50675133)the National Basic Research Program (973) of China (No. 2006CB705401)
文摘The dynamic recrystallization(DRX) behaviors in SPHC steel were investigated with hot compression tests at deformation temperatures of 950-1 150,strain rates of 0.1-15 s-1,and initial austenite grain sizes of 86-232 μm.The effects of deformation temperature,strain,strain rate and the initial austenite grain size on the microstructural evolution during DRX were studied in detail.The results show that DRX is observed under the condition of the Zener-Hollomon parameter being less than 1.07×10 13 s-1.The deformation activation energy for SPHC steel is calculated to be 299.4 kJ/mol by regression analysis.Austenite grain size of DRX is refined with decreasing temperature and increasing strain rate under steady state conditions,but it is not influenced by the initial grain size.The mathematical equation of DRX grain size of SPHC steel is obtained.
